As known, for example from U.S. Pat. No. 3,741,614, a railway vehicle is supported by a series of railway axles, each of which consists of an axle on which the wheels are fitted; each axle end is supported by a device comprising a railway axle box restrained by means of appropriate suspensions to the railway car. Each axle box comprises a rolling bearing mounted on a reduced diameter end of the axle, named journal. The inner ring of the rolling bearing is mounted and axially locked on the journal of the axle between a shoulder, carried integrally by the axle, and a blocking end cap, which is integrally restrained to the free end of the journal, in particular to a frontal surface thereof, by means of screws.
The blocking end cap is subject to relatively high stresses which may produce elastic deformation by bending. The center of the blocking end cap, which end cap is normally made as a concave disc, deflects towards the journal, while a peripheral outer edge of the cap deflects so as to axially move away from the bearing. These deformations, however small, may create many drawbacks because of the narrow spaces and presence of possible wheel rotation detection devices. Consequently, the blocking end cap is currently made as a relatively rigid element, so as to either limit or avoid deformation, at the cost of a heavy weight of the cap, nowadays less and less acceptable.